It is frequently desirable to construct subterranean walls comprised of granular material. For example, it is known in the art that subterranean walls comprised of pervious granular iron material are particularly useful in treating certain pollutants in contaminated ground water, including, for example, trichloroethylene (T.C.E.) and other chlorinated solvents. Indeed, the oxidation of the granulated iron from such subterranean walls chemically neutralizes chlorinated solvents in the ground water. In this way, the granular iron from such subterranean walls acts as a corrective filter that treats the contaminated ground water.
While such subterranean walls are clearly useful in treating contaminated ground water, there are problems involved in their construction. For example, one known technique for constructing subterranean walls involves excavating a trench with a backhoe or the like, and then filling the trench with granular material. This particular technique, however, suffers from some obvious deficiencies. Namely, it is time consuming, labor intensive, expensive, and unsuited for use in constructing deep walls. In addition, this technique is also generally unreliable in terms of controlling the width of the wall.